/**
 * @desc 兼容不同的浏览器居中scrollCenter
 * @author 张慧华 z@j-ui.com
 */
(function ($) {
    $.fn.extend({

        getWindowSize: function () {
            if ($.browser.opera) {
                return {width: window.innerWidth, height: window.innerHeight};
            }
            return {width: $(window).width(), height: $(window).height()};
        },
        /**
         * @param options
         */
        scrollCenter: function (options) {
            // 扩展参数
            var op = $.extend({z: 1000000, mode: "WH"}, options);

            // 追加到 document.body 并设置其样式
            var windowSize = this.getWindowSize();

            return this.each(function () {
                var $this = $(this).css({
                    'position': 'absolute',
                    'z-index': op.z
                });

                // 当前位置参数
                var bodyScrollTop = $(document).scrollTop();
                var bodyScrollLeft = $(document).scrollLeft();
                var movedivTop = (windowSize.height - $this.height()) / 2 + bodyScrollTop;
                var movedivLeft = (windowSize.width - $this.width()) / 2 + bodyScrollLeft;

                if (op.mode == "W") {
                    $this.appendTo(document.body).css({
                        'left': movedivLeft + 'px'
                    });
                } else if (op.model == "H") {
                    $this.appendTo(document.body).css({
                        'top': movedivTop + 'px'
                    });
                } else {
                    $this.appendTo(document.body).css({
                        'top': (windowSize.height - $this.height()) / 2 + $(window).scrollTop() + 'px',
                        'left': movedivLeft + 'px'
                    });
                }

                // 滚动事件
                $(window).scroll(function (e) {
                    var windowSize = $this.getWindowSize();
                    var tmpBodyScrollTop = $(document).scrollTop();
                    var tmpBodyScrollLeft = $(document).scrollLeft();

                    movedivTop += tmpBodyScrollTop - bodyScrollTop;
                    movedivLeft += tmpBodyScrollLeft - bodyScrollLeft;
                    bodyScrollTop = tmpBodyScrollTop;
                    bodyScrollLeft = tmpBodyScrollLeft;

                    // 以动画方式进行移动
                    if (op.mode == "W") {
                        $this.stop().animate({
                            'left': movedivLeft + 'px'
                        });
                    } else if (op.mode == "H") {
                        $this.stop().animate({
                            'top': movedivTop + 'px'
                        });
                    } else {
                        $this.stop().animate({
                            'top': movedivTop + 'px',
                            'left': movedivLeft + 'px'
                        });
                    }

                });

                // 窗口大小重设事件
                $(window).resize(function () {
                    var windowSize = $this.getWindowSize();
                    movedivTop = (windowSize.height - $this.height()) / 2 + $(document).scrollTop();
                    movedivLeft = (windowSize.width - $this.width()) / 2 + $(document).scrollLeft();

                    if (op.mode == "W") {
                        $this.stop().animate({
                            'left': movedivLeft + 'px'
                        });
                    } else if (op.mode == "H") {
                        $this.stop().animate({
                            'top': movedivTop + 'px'
                        });
                    } else {
                        $this.stop().animate({
                            'top': movedivTop + 'px',
                            'left': movedivLeft + 'px'
                        });
                    }

                });
            });

        }
    });
})(jQuery);